Humans have applied scents and fragrances to their skin since antiquity. Originally these aesthetically pleasing materials were commonly isolated in raw form as resins, gums or essential oils from natural sources, inter alia, the bark, roots, leaves and fruit of indigenous plants. These resins, gums, and oils were directly applied to the body or diluted with water or other solvent, including in some cases, wine. With the advent of modern chemistry, individual components responsible for the odor properties of these resins, gums and oils were isolated and subsequently characterized. Aside from common “perfume vehicles” inter alia, fine perfumes, colognes, eau de toilettes, and after-shave lotions, a wide variety of personal care or personal hygiene items also deliver for aesthetic reasons fragrance notes, accords, or fragrance “characteristics”.
It is well known that mixtures of perfume or fragrance raw materials when deposited on the skin lose intensity and may change character with time, mainly due to factors such as differential evaporation and skin penetration. Many attempts have been made to minimize these drawbacks, but so far without notable success. Particularly, efforts have been made to prolong the diffusion, as well as to improve other characteristics of fragrance materials, by e.g. increasing the fragrance raw material concentration or by using additives such as silicones, glycerol, polyethylene glycols and so on. Such additions, however, have never been adequate to increase the longevity of the fragrance odor.
In addition to alcohols and esters, aldehydes and ketones form the most commonly delivered fragrance raw materials. Alcohols and esters can be suitably released in a delayed manner from an orthoester pro-accord or pro-fragrance. The controllable release of these fragrance raw materials thus provides the formulator with a means for delivering these fragrance ingredients, not only as an accord, but in a delayed-releasable manner over a period of time fragrance which is desirable to the fine fragrance and perfume user. However, the primary means for delivering aldehydes and ketones in a time-releasable manner has typically been the acetal and ketal pro-fragrance. Notwithstanding the fact that these materials are capable of delivering the required aldehyde and ketone under the proper acidic conditions, in the past, because there was no means of adjusting the release profiles of pro-fragrances, these compounds have not provided the formulator with a highly controllable method for sustained and predictable delivery of aldehydes and ketones.
Accordingly, there remains a need in the art for a pro-accord which can be formulated into fine fragrances, perfumes, personal care and personal hygiene products wherein aldehyde and ketone fragrance raw material components can be released in a highly controllable manner to provide enhanced fragrance longevity.